A display device including a laser beam generation portion outputting a laser beam is known in general. Such a display device is disclosed in Japanese Patent Laying-Open No. 2001-189520, for example.
In Japanese Patent Laying-Open No. 2001-189520, there is disclosed a projection type display device including a plurality of light-emitting laser diodes (laser beam generation portions) driven by receiving modulated current, an optical scanning portion projecting a picture by scanning laser beams and a modulation control portion supplying the modulated current to the light-emitting laser diodes. This projection, type display device according to Patent Document 1 oscillates laser beams having relaxation oscillation by supplying the modulated current to the laser diodes for a period shorter than a period when relaxation oscillation occurs at the initial lasing stage, and projects a picture by employing the laser beams having the relaxation oscillation (whose outputs are unstable). Thus, the projection type display device inhibits the picture from being projected in a state where a plurality of laser beams interfere with each other by projecting the picture with the laser beams whose outputs are unstable. The projection type display device thereby suppresses occurrence of speckle noise (white dotlike unevenness appearing in the projected picture) resulting from interference between the laser beams.